The pulley is well known. Pulleys have been a part of enabling the lifting of loads. By using a fixed pulley, the direction of force is changed. Changing the direction of the force allows a load to be lifted without pulling from above the load. Using a movable pulley enables less force to be exerted to lift a load, than lifting that same load without the moveable pulley. While the pulley has been around for hundreds of years, advances in technology have led to improvements in the construction of the pulley itself as well as in the ropes or lines with which pulleys are used.
Early models of pulleys used wood for the wheels and frames, while the rope was typically constructed of natural fibers such as hemp. These materials are adequate for certain applications. However, modern advances allow smaller, lighter, and stronger pulleys to be constructed. Not only can the frames and wheels be made smaller, lighter, and stronger but the line which works with pulley can also be made smaller, lighter, and stronger.